The ear / hearing system consists of two parts (peripheral and central).
The peripheral part includes the auricle with the external auditory canal, the middle ear and the inner ear (labyrinth) and the 8th cranial nerve (Vestibulocochlear nerve), which forwards all information from the ear to the brain.
To the central share belongs to the auditory and equilibrium tracts. These are connections between nerves that arise from the auditory or Balance organ and run from there over long paths and intermediate stations to their destination, the brain.
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According to functional aspects, the ear is divided into one Outer ear with auricle and external ear canal, in the Middle ear With eardrumEar trumpet, tympanic cavity and ventilated rooms and in the Inner ear (labyrinth) with the Hearing and balance apparatus.
A - outer ear - Auris externa
B - middle ear - Auris media
C - inner ear - Auris interna
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The auricle in the ear is one of the peculiarities of every person. No auricle is the same as the other and one encounters a variety of shapes (flat ears, Protruding ears, attached earlobes, etc.).
Except for Earlobe the auricle is formed by elastic cartilage and covered by skin. Protruding folds and indentations are denoted by various Greek terms (Tragus and Antitragus, Helix and Antehelix, Crura anthelices, Cavum conchae).
The function of the auricle is to capture sound. Many animals can even point their ears towards the sound source. We humans could theoretically do this too, if the small adjusting muscles in the ear were not atrophied. However, some people can still wiggle their ears today.
The external auditory canal (meatus acousticus externus) connects the auricle with the eardrum. It consists of an approximately 3 cm long and 6 mm wide duct, which consists of cartilage on the outside and bone on the inside. Cartilaginous and bony parts are kinked against each other. Thus foreign bodies cannot directly injure the eardrum. So that the doctor still has a good view with the ear mirror (otoscope) when examining the eardrum, he pulls our auricle back a little.
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Of the outer ear canal is lined with hair and sebum glands, the fluid (secretion) of which is removed from the skin together with flaked horn parts Ear wax (Cerumen) forms. Narrow ear canals prevent the wax from being transported outside and can cause a Hearing loss cause
You can also find more anatomical details under our topic: Outer ear
To the Middle ear (Auris media; Otos media; Middle ear) include:
The eardrum (Tympanum ) is a membrane-like barrier between the external auditory canal and the tympanic cavity. With its 0.1 mm thickness it is wafer-thin, oval and has a diameter of about 8 mm. The middle ear is covered with skin on the outside and mucous membrane on the inside. During the ear mirror (Otoscopy) the eardrum is examined carefully, as the smallest changes can give an indication of diseases around the ear. In a healthy state, it has a gray-yellow sheen and reflects a light reflection from the ear mirror (otoscope).
One of the three ossicles in the ear (Hammer = Maleus, anvil = Incus, stirrup = Stapes) is fused with the eardrum from the inside, so you can see the hammer handle in the upper section of the eardrum during an examination.
This place in the ear is very thin and sensitive to pressure. Differences in pressure, caused by illnesses, show up here in the form of indentations or depressions. At an extreme Otitis media) the pus that has developed will look for its drainage to the outside through precisely this point.
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The Tympanic cavity in the ear (Cavitas tympanica) is a pearl-sized room and contains the Auditory ossicles (hammer = Maleus, anvil = incus, stapes = stapes). Transfer and strengthen the ossicles (Impedance) the sound waves from the eardrum to the Inner ear. They are the smallest bones that can be found in the human body and are connected to one another by small joints. Six different walls separate the tympanic cavity from other important organic structures.
At Inflammation of the tympanic cavity in the ear (Otitis media) these neighboring structures can be affected and cause severe inflammatory disease processes. The eardrum represents the outer wall. Inward, the tympanic cavity is formed by the oval and round window of the Inner ear severed. A thin but very important facial nerve runs right between these two windows. For middle ear infections is the 7. Cranial nerve (facial nerve; Facial nerve) endangered and can lead to a Facial paralysis (Facial palsy) to lead.
The tympanic cavity is separated from the ear trumpet towards the front. The back wall in the ear is adjacent to a bony structure - mastoid process (Mastoid, mastoid process) - which contains small air spaces (pneumatized). Here, too, the 7th cranial nerve runs in a canal and can cause inflammation of the mastoid process (Mastoiditis) are damaged. On the floor, the tympanic cavity in the ear borders on a large jugular vein (Internal jugular vein).
Further information can also be found at: Mastoiditis
The Eustachian tube (auditory tuba, Eustachian tube, pharyngotympanic tuba) connects the middle ear with the nasopharynx and is used to equalize pressure in the ear when overcoming greater heights while diving, mountaineering and flying. This is because there is a pressure difference between the external auditory canal and the Middle ear.
You can also find more anatomical details under our topic: Middle ear
In the inner ear (Auris interna; Labyrinth; inner ear) is the Cochlea (Cochlea) where the sound in Nerve impulses is converted. That's right next door Balance organ (Semicircular canals, vestibular organ).
In contrast to the Middle ear is this Inner ear filled with fluids, the so-called peri- and endolymph. Both liquids have different chemical compositions. The skull bone in which the Inner ear is called the petrous bone and gives an exact shape (bony labyrinth). The snail also becomes a bony labyrinth (Cochlea), in which the hearing organ is located, the atrium in the ear (vestibule), the bony semicircular canals in which the organ of equilibrium lies and the internal auditory canal (Meatus acousticus internus) with the auditory and balance nerves (Nervus vestibulocochlearis, nervus staticoacusticus, 8th cranial nerve) is included.$config[ads_text1] not found
The snail (cochlea) and the hearing organ (organ of Corti)
The hearing organ in the ear lies within the bony cochlea (Cochlea). The snail turns in a spiral around its own axis. It consists of three canals lying one on top of the other, the timpani staircase (Scala tympani), the snail (Cochlear duct) and the courtyard stairs (Scala vestibuli). There are thin skins between the three courses (Membranes) (Reissner's membrane and basilar membrane), which increase when injured Hearing loss or Tinnitus can lead (e.g. Meniere's disease). The actual sense organs for hearing are located in the cochlea in the ear, where mechanical waves are converted into nerve impulses.
You can also find more anatomical details under our topic: Inner ear
Especially with To fly with a commercial airplane we notice a strange feeling of pressure in the ear. With a self-experiment you can imitate this feeling and check the function of the ear trumpet (Valsalva attempt): You hold your nose, close your mouth and blow against it with pressure. A feeling of pressure should now build up in the ear because air is pressed through the ear trumpet into the middle ear and the eardrum bulges outwards.
For inflammation (pharyngitis, sniff (Rhinitis)) the surrounding tissue in the nasopharynx can swell so much that the eustachian tube becomes too narrow in the ear and can no longer fulfill its function as a pressure equalizer. At flu-like infections a similar feeling of pressure can therefore arise. When swallowing, yawning or artificial air pressure, as the divers are taught, the perceived pressure difference can usually be compensated for in healthy people.
The organ of equilibrium in the ear
The human Balance organ registers two types of acceleration: linear acceleration and angular acceleration. Straight-line acceleration in our ears we hear when a car hits, when we are pushed into the seat or when we would fly up in a rocket. Angular acceleration means any change in our head position from the upright position.
For the registration of the straight line acceleration there are two Atrial sac (Utricle and saccule) in the ear. They are equipped with sensory cells that are bent when accelerated in a straight line. When bent, they are excited and send signals to the brainso that we are aware of the acceleration.
That stands for the perception of the angular acceleration Semicircular canal system available in the ear. Since we have to perceive changes in our position in all three dimensions, we have three semicircular canals. They are filled with a liquid (Endolymph). When the head moves, this liquid stops because of its inertia and bends a sensor (dome, Cupula) in the semicircular canal. The dome is deflected against the head movement and registers a change in speed (= acceleration). The faster the head position is changed, the more the dome is deflected.
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Both sensor systems - the sensory cells of the atrial sacs and the domes of the semicircular canals - are connected to one nerve (Vestibulocochlear nerve, 8th cranial nerve) in connection, which sends all information about changes in position to the brain. If the sensor system is damaged (e.g. when suffering from paroxysmal positional vertigo (BPLS), more benign Positional vertigo) or the 8th cranial nerve becomes inflamed (Vestibular neuritis), we feel dizziness.
You can also find more information at: dizziness